An example of a multimedia computer system which converts an input RGB signal to a luminance signal and a color-difference signal, extracts a characteristic point in the luminance signal every frame, corrects the luminance signal and the color-difference signal, and conducts display is disclosed in JP-A-2002-132225 (page 4 and FIG. 1).
Furthermore, it is disclosed in JP-A-2005-26814 to provide a side panel detection circuit which detects a side panel and conduct picture quality according to a result of the side panel detection and a result of video luminance level detection.